The purpose of this project is to conduct research in statistical methods and computer techniques with particular emphasis on those appropriate for analyzing data from clinical, diagnostic, and prevention trials and epidemiologic studies of cancer. Many of the problems studied under this project arise from the consultative activities of the Section. Important activities during the past year have included accounting for the effect of measurement error and intra-individual variation in analyzing the relation of diet to breast cancer; investigating methods for analyzing complex sample survey data, including ways of incorporating the clustering and weighting of the observations into regression analyses of epidemiologic studies, and approaches to analyzing data from large national health surveys such as the National Health and Nutrition Examination Surveys (NHANES) and the National Health Interview Surveys (NHIS); comparisons of approaches to significance testing for quasi-experimental designs (motivated by a study of a supermarket intervention); and methods for analysis of survival data with dependent censoring. Finally, the Section has continued to maintain and improve software for interactive analysis of complex medical data using sophisticated multiple regression techniques and survival analysis. These programs are operational on the NIH Convex Computer system.